This invention relates to real-time measurements of transport of different fluids into one or more barrier coatings, and more specifically, to a sensor device having a protective overlayer, and systems and methods of using same.
Barrier coatings, such as polymers, are used for many applications, such as for packaging and for providing a protective layer on another coating. As barriers, these materials typically separate a system, such as an electronic component, a part of an engineering structure, or an article of food, from an environment. Often, such coatings are applied from liquid coating formulations. To adjust viscosity of the formulations, a wide variety of organic solvents are used. These solvents may be problematic, however, when screening new coating formulations using sensor devices.
For example, in the combinatorial discovery of coating materials for application as barrier coatings, rapid evaluation of a barrier property such as permeability of the coatings is of primary importance. The plurality of combinatorial coatings may be applied to a sensor responsive to a particular analyte, or material of interest, for which the barrier properties of the array of coatings is measured. The material of the sensing layer of these sensors, however, is often altered or dissolved by any solvent that may be present in the coating. Thus, screening of such coatings results in inaccurate results, delaying the combinatorial discovery process.
There remains an unmet need for the speedy and accurate evaluation of minute samples of barrier coating compositions, especially those compositions including solvents. There is a further need for sensing materials, devices, and methods that are not affected by common organic solvents used in barrier coatings. There is yet a further need for methods of use in conjunction with such materials and devices that provide the capability to map spatial variations of a barrier property, such as permeability, across a single barrier coating or an array of coatings.
The present invention discloses methods and devices for measurement of properties of materials of interest, such as permeability of barrier coatings. These measurements are accomplished using, for example, a solvent-resistant polymeric material to determine oxygen barrier properties of liquid-deposited coating arrays. In one embodiment, the oxygen-permeability measurement method disclosed provides the capability to map spatial variations of permeability across a single barrier coating or an array of coatings. In this embodiment, a fluorophore that exhibits fluorescent quenching upon exposure to molecular oxygen is incorporated in a solvent resistant sensor structure. An array of barrier coatings is applied onto the sensor. Upon exposure of the coating array to oxygen, the coating permeability is determined by the time-dependent change in the luminescence signature of the immobilized fluorophore under the barrier coating. This luminescence signal is then compared to the signal produced from a reference spatial region containing a bare sensor or a reference coating material.
To achieve the stated and other advantages of the present invention, as embodied and described below, the invention includes a device for luminescence mapping of barrier coatings, the device comprising: a luminescence sensor having at least one external surface; a chemically sensitive overlayer applied to at least one of the at least one external surface; an array of barrier coatings in a library deposited onto the chemically sensitive overlayer; a material of interest for exposure to the array of barrier coatings; and a measurement device for measuring variation in luminescence for the array of barrier coatings exposed to the material of interest.
To achieve the stated and other advantages of the present invention, as embodied and described below, the invention includes a method for measuring barrier properties of barrier coatings, the method comprising: providing a luminescence sensor having at least one external surface; applying a chemically sensitive overlayer to the at least one external surface of the luminescence sensor; placing an array of barrier coatings on the chemically sensitive overlayer; exposing the array of barrier coatings to an exposure material of interest; and measuring variation in luminescence of the array of barrier coatings.
Additional advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become more apparent to those skilled in the art upon examination of the following or upon learning by practice of the invention.